Name: Answer Key
Date:
ACIDS, BASES, & THE pH SCALE
Pd:
PART 1: ACIDS AND BASES
Comparing Acids and Bases
Acids
Bases (Alkalines)

Sour taste, leaves burning sensation

Sharp bitter taste, feels slippery to touch

Increase hydrogen ions (H+) in solution

Decrease hydrogen ions (H+) in solution
(Increase hydroxide ions (OH-) in solution)

Example: HCl

Example: NaOH

Turns litmus (pH) paper to red

Turns litmus (pH) paper to blue
H+ + Cl-
Na+ + OH-
PART 2: THE pH SCALE


The pH Scale is a measurement of how acidic or how basic a solution is.


Compounds are acidic if they have a pH lower than 7.
Compounds with a pH higher than 7 are basic or alkaline.
Compounds with a pH of 7, are neutral.

The scale goes from 0 to 14.
1
0
2
3
4
5
6
7
8
Increased concentration of H+ ions
Decreased concentration of OH- ions
pH below 7 = acids
9
10
11
12
13
Decreased concentration of H+ ions
Increased concentration of OH- ions
pH at 7 = neutral
(pure water)
pH above 7 = bases
PART 3: BUFFERS


A buffer is a weak acid or base that prevents sudden changes in pH.
o Maintains homeostasis
A buffer works by binding to H+ ions releasing H+ ions when the solution pH changes.


Buffers bind to H+ ions when the concentration of H= ions in solution increases.

Buffers release H+ ions when the concentration of H= ions in solution decreases.
HCl
H+ + Cl-
NaOH
14
Na+ + OH- (The OH- will bind to H+ ions to form H2O – neutralization)
ACIDS, BASES, & THE pH SCALE
Biology
Name:
Date:
Pd:
PART 1: ACIDS AND BASES
Comparing Acids and Bases
Bases_____ (Alkalines_____)
Acids_____

Sour_____ taste, leaves burning_____sensation



Sharp bitter_____ taste, feels slippery_____ to
touch
Increase_____ hydrogen ions (H+) in solution
(Increase_____ hydroxide ions (OH-) in
solution)

Decrease_____ hydrogen ions (H+) in solution
(Increase_____ hydroxide ions (OH-) in
solution)

Example: HCl_____

Example: NaO_____H

Turns litmus_____ (pH) paper to red_____

Turns litmus (pH) paper to blue_____
H+ + Cl-_________
Na+ + OH-________
PART 2: THE pH SCALE


The pH Scale_______ is a measurement______________ of how acidic or how basic a solution is.


Compounds________ are acidic_________ if they have a pH lower_______ than 7___.
Compounds with a pH higher__________ than 7____ are basic__________ or alkaline____________.
Compounds with a pH of 7_________, are neutral___________.

0
The scale goes from 0____ to 14____.
1
2
3
4
5
6
Increased_______ concentration of H+____ ions
Decreased_______ concentration of OH-____ ions
pH below 7 = acids____
7
8
9
10
11
12
13
14
Decreased______ concentration of H+___ ions
Increased______ concentration of OH-___ ions
pH at 7 = neutral____
(pure_____ water_____)
pH above 7 = bases_____
PART 3: BUFFERS


A buffer_____ is a weak _____ _____ acid or _____ base that _____ prevents sudden _____ changes in pH.
o Maintains homeostasis________
A buffer works by binding_____ to H+ ions releasing______ H+ ions when the solution pH changes.


Buffers bind_____ to H+ ions when the concentration________ of H= ions in solution increases_____.
NaOH________
Na+_____ + OH-_____ (The OH- will bind to H+ ions to form H2O – neutralization_____)

Buffers release_____ H+ ions when the concentration________ of H= ions in solution decreases_____.
HCl_____ _____
H+ + Cl-_____